If the air fuel ratios were correct throughout the rev range then you would think the carby is ok. Incorrect ignition timing/ bad spark should also upset the A/F ratio so maybe it is something else. Have you thought about valve clearances?

I can't see how the air/fuel ratio could be correct if it is running horribly, especially missing?

Thats what we thought...

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67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

The advance curve makes a heap of difference.
A standard Cooper S dizzy curve is miles away from what it wants. You want 10 or 12 deg at 1000rpm idle, and 30-32deg max @3500, then flat line all the way. If 2deg out, you will feel the HP loss.
As for the 135psi compression pressure, it sounds way too low to me. I would expect 180psi. But I don't have a comp gauge so mine has never been checked.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

My last car was a 1330 mild cam, 11:1 and 160psi

I would like to hear what compression people are measuring with a large cam. The longer it takes for the intake valve to close the lower the compression test. We usually refer to our CR using the swept area when in actual fact the piston may be well past BDC before the intake valve closes. (Dynamic Compression Ratio)

Silly question was it going ok before you ran it on the dyno.

What did they change. Jets, choke size. ? Timing, This may give you a clue.

As per Kevs comments a proper curved dizzy makes a hugh difference to a car

I would go back to basics. Points plugs leads timing

To all the people who responded and those who sent pm's, I'm most grateful and appreciative.
Unfortunately something came up which has put the Mini on the back burner.
One thing is clear, when time permits I need to sort out the ignition advance curve. This raises the question:
Do I spend money ($150-$200 depending on condition) on my Cooper S distributor, or bite the bullet and pay $550 odd for a new beaut electronic device? At the back of my mind is the simplicity of a points system. i.e. When touring through Indonesia I carried with me a spare set of points, rotor button and condensor which covered most possibilities. (As it turned out I needed none of my spares except an oil filter). Would I be more vulnerable with a "black box" system if I go touring again....?
Once I've got the ignition side of things sorted, I can focus on the other issues I have..

Thanks very much again,

Michael

_________________
67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

If by black box you mean a Stealth? It is possible to connect the magnetic pick up wires direct to the coil and bypass the Stealth in the event of a failure (if you plan enough slack in the wiring). Depending on what static advance you set it on initially, the solution in that instance would be to advance the dizzy to give it more advance in order to limp the car to a place or repair/home etc as applicable. It may not run well, but it can become drivable. If you mean an 123Ignition or 123Tune; or a pulsar conversion etc then a failure could leave you on the side of the road unless you carry a spare dizzy to swap over.

I would advise sorting out the existing problem first though, or you are just adding another variable to your problem. What you suggest can be an improvement down the track unless you absolutely determine the dizzy is at fault.

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There is nothing wrong with the old points system provided everything is in good condition. Start with the basics and move forward. IMHO 130psi is ridiculously low but doesn't surprise me as I have come across very few people who actually know how to calculate compression ratios properly, and lets not even start on cam timing. My advice would be to start first with the dizzy. Its not expensive to have it re-graphed but they do wear and lead to inconsistent spark. The dizzy curve is not a one size fits all and you can spend plenty of time and money chasing the last few horses but start with something basic. Ask your profiler to give you 10deg in the dizzy and all in by 3000rpm. That gives you effectively 20 degrees advance in the distributor, because the distributor is spinning at half crank speed, so you double the degrees of rotation in the plate. Dial it in then at 10deg BTDC with your timing light. This will give you 30deg total advance all in by 3k. Its a nice safe amount for a street engine on 98. Having 10degrees of lead will make it a little hard to turn over as the spark is firing prematurely down the cylinder, makes it easier to set the idle without the engine running on when you shut the ignition off. The dyno operator is correct in saying that the head, cam and carb need all match each other. There is nothing wrong with a weber although Doc is right IMO the 34 chokes are too small, a 36 is good and a pair of 38 are fine if you are using a larger cam and spend a fair bit of time up the rev range. I am not familiar with your head design and calculating comp ratio without removing the pistons is inaccurate. You can get an idea if you pop the head and CC the chambers. You need to measure Bore, stroke, piston dish, top ringland CC and allow 2.8cc for the head gasket. You also need to accurately measure the distance between the piston and top of the block, ALL this is needed to accurately determine the comp ratio. Everything except the ringland can be determined with the pistons in, but we can take a close guess at this if need be. If you don't know how to do this PM me and I will guide you through it. For the street 11:1 is very high for 98 fuel but I doubt yours is anywhere near this. My guess is pretty similar to a standard 1100S, but we don't know the accuracy of the guage used to measure the pressure anyway, so if you really want to know pop the head.

The next big thing I would question is the compatibility of the cam with the head and the cam timing. Who timed it in for you? Actually this question doesn't matter. I'd still check it yourself. Deal with one thing at a time and feel free to PM me if you need some guidance.
G.

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1970 Cooper S ex-Bathurst & ATCC
1964 Austin Cooper S ex-Group C race car
1967 Morris Cooper S ex-Group B
1962 Mini Speed sports sedan
1968-71 ex-Peter Manton Shell car

You could get an electronic Scorcher dissy made by Performance Ignition Services in Melbourne which they will build with a custom curve to suit your engine specs. These use all commonly available and cheap Bosch parts as found in many Fords and Holdens. They even provide you with a card that has all the replacement Bosch parts should you ever need them which in my experience it never has. They also tell you what to set the idle timing at.

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Slide
1965 Mini Van (1360)
1970 Mk2 Cooper S (1310)
1978 Rover SD1 V8 (4.6)
1996 Land Rover Discovery V8 (4.0)

Great information and help from low n blown. This is what this forum is all about. Everyone trying to help each other. Great stuff.

Quick update:

Rejetted the Carby. Think it goes better but hard to tell, the roads are too wet...

Retested the compression pressures, all about 205 psi which is much more like it. The dyno blokes gauge is obviously u/s...

Next is the dizzy..

Cheers

Michael

_________________
67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..